send-pack: fix parsing of --force-with-lease option

The last argument for parse_push_cas_option() is if it is "unset"
(i.e. --no-force-with-lease), and we are parsing the option with an
explicit value here, so it has to be 0.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
push: teach --force-with-lease to smart-http transport

We have been passing enough information to enable the
compare-and-swap logic down to the transport layer, but the
transport helper was not passing it to smart-http transport.

Signed-off-by: Junio C Hamano <gitster@pobox.com>